A guy encounters an elephant while on a safari in Africa.
It’s in pain and laying on the ground. He looks into it and discovers a thorn in its foot.
He takes it off, and the elephant trots away cheerfully.
The same guy is standing in London, fifteen years later, watching a circus procession pass by.
When an elephant approaches him, it stops, looks him in the eyes, reaches out with its trunk, lifts him into the air, and crushes him into the ground.
It was a different elephant.
This joke is included in the Black Book of Jokes. You can order it from here.